Female sterilization is a very common practice and is performed frequently throughout the world. Traditionally, the most common female sterilization method is fallopian tube ligation, a procedure that utilizes a trans-abdominal approach for the occlusion, or tying, of the fallopian tubes. Despite its worldwide use, tubal ligation via the trans-abdominal approach is associated with substantial trauma, discomfort, hospital stays, and complications, such as bleeding, infection, reactions to general anesthetic, and bowel perforation. The trans-abdominal approach involves surgery, is difficult to reverse, and is not readily available to many women throughout the world. Even though local anesthetic is considered an option for the trans-abdominal approach to tubal ligation, almost all of these sterilization procedures are performed under general or spinal anesthesia. In addition, the trans-abdominal approach to tubal ligation requires incisions that invade the peritoneal cavity, thereby raising the risk of injury to intra-abdominal structures.
In order to avoid the problems associated with trans-abdominal tubal ligation procedures, various trans-cervical approaches to tubal sterilization have been proposed. The trans-cervical approach to sterilization involves the insertion of a catheter or sterilization device directly into the fallopian tubes via the reproductive tract, eliminating the need for general anesthetic and abdominal incisions. Initial trans-cervical approaches to tubal sterilization involved radiofrequency, chemical or heat induced scarring, or liquid silicone injections. However, these approaches have all failed due to safety and efficacy concerns. Chemical scarring agents, such as quinacrine, iodine, and methylcyanoacrylate, require repeated applications and have problems concerning biocompatibility. Thermal blocking procedures, which induce the formation of scar tissue within the fallopian tubes, have high failure rates and major complications such as uterine bleeding and bowel perforation. Electrocautery methods, which employ an electric current to induce scar tissue within the fallopian tubes, are also unsatisfactory because they do nor scar a sufficient amount of tissue and because they can burn surrounding organs, particularly the bowel.
Current trans-cervical methods involve occluding the fallopian tubes by implanting a small occluding device. The occluding devices in the prior art are usually in the form of a cylindrical plug or a coil. For instance, Loy in U.S. Pat. No. 6,357,443 describes a removable fallopian tube plug consisting of a tubular (cylindrical) elongate member with a number of fingerlike protrusions that extend radially outwards creating a barrier and thereby occluding the fallopian tubes. Additionally, Saadat et al. in U.S. Pat. No. 5,935,137 describe a fallopian tube occluding device for female sterilization which is a plastic, rubber, or metal elongate hollow tubular (cylindrical) structure with ribs that are either coated with copper or are interlaced with copper rings. The hollow portion of this device has a valve, or seals with a hydrogel, after the device is implanted into the fallopian tubes.
Coils, which have a helical outer surface and which assume a bent shape when released from the delivery catheter system, are also used to occlude the fallopian tubes. For example, Ton et al. in U.S. Pat. Nos. 5,601,600 and 5,746,769 describe the use of a coil to occlude the fallopian tubes. The device consists of polyethylene terephthalate (PET) fibers wrapped around a stainless steel core that is surrounded by 24 or more coils of nickel-titanium alloy. After the device is deployed within the fallopian tubes, the PET fibers induce the tubal epithelium to undergo fibrosis, which results in tubal occlusion. The device also relaxes to its natural bent shape once it is deployed in the fallopian tube. The tubal occlusion process from these devices takes about three months to complete and must be confirmed via a hysterosalpingogram.
U.S. Pat. No. 7,846,160 teaches the use of an exterior screw thread to advance a lumen plug by rotation In FIG. 3. In FIG. 4 barbs are held under a sheath such that when the sheath is retracted, the barbs spring out and point proximally to prevent removal.
Most of these devices eventually become dislodged or have found to be only moderately effective in preventing pregnancy. In addition, all of the fallopian tube occluding devices are either composed of metal or have metal components. As a result, various surgical procedures involving electrosurgery, radiofrequency, or microwave energy cannot be performed near the implants. Therefore, a need exists for a female contraceptive device that does not contain any metal, does not migrate once implanted, and which provides immediate protection against conception. The occlusion device of the present invention fulfills these needs.